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// Copyright 2020 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package vfs2
import (
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/sentry/arch"
"gvisor.dev/gvisor/pkg/sentry/kernel"
"gvisor.dev/gvisor/pkg/sentry/vfs"
"gvisor.dev/gvisor/pkg/syserror"
)
const allFlags = linux.IN_NONBLOCK | linux.IN_CLOEXEC
// InotifyInit1 implements the inotify_init1() syscalls.
func InotifyInit1(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
flags := args[0].Int()
if flags&^allFlags != 0 {
return 0, nil, syserror.EINVAL
}
ino, err := vfs.NewInotifyFD(t, t.Kernel().VFS(), uint32(flags))
if err != nil {
return 0, nil, err
}
defer ino.DecRef()
fd, err := t.NewFDFromVFS2(0, ino, kernel.FDFlags{
CloseOnExec: flags&linux.IN_CLOEXEC != 0,
})
if err != nil {
return 0, nil, err
}
return uintptr(fd), nil, nil
}
// InotifyInit implements the inotify_init() syscalls.
func InotifyInit(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
args[0].Value = 0
return InotifyInit1(t, args)
}
// fdToInotify resolves an fd to an inotify object. If successful, the file will
// have an extra ref and the caller is responsible for releasing the ref.
func fdToInotify(t *kernel.Task, fd int32) (*vfs.Inotify, *vfs.FileDescription, error) {
f := t.GetFileVFS2(fd)
if f == nil {
// Invalid fd.
return nil, nil, syserror.EBADF
}
ino, ok := f.Impl().(*vfs.Inotify)
if !ok {
// Not an inotify fd.
f.DecRef()
return nil, nil, syserror.EINVAL
}
return ino, f, nil
}
// InotifyAddWatch implements the inotify_add_watch() syscall.
func InotifyAddWatch(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
fd := args[0].Int()
addr := args[1].Pointer()
mask := args[2].Uint()
// "EINVAL: The given event mask contains no valid events."
// -- inotify_add_watch(2)
if validBits := mask & linux.ALL_INOTIFY_BITS; validBits == 0 {
return 0, nil, syserror.EINVAL
}
// "IN_DONT_FOLLOW: Don't dereference pathname if it is a symbolic link."
// -- inotify(7)
follow := followFinalSymlink
if mask&linux.IN_DONT_FOLLOW == 0 {
follow = nofollowFinalSymlink
}
ino, f, err := fdToInotify(t, fd)
if err != nil {
return 0, nil, err
}
defer f.DecRef()
path, err := copyInPath(t, addr)
if err != nil {
return 0, nil, err
}
if mask&linux.IN_ONLYDIR != 0 {
path.Dir = true
}
tpop, err := getTaskPathOperation(t, linux.AT_FDCWD, path, disallowEmptyPath, follow)
if err != nil {
return 0, nil, err
}
defer tpop.Release()
d, err := t.Kernel().VFS().GetDentryAt(t, t.Credentials(), &tpop.pop, &vfs.GetDentryOptions{})
if err != nil {
return 0, nil, err
}
defer d.DecRef()
fd = ino.AddWatch(d.Dentry(), mask)
return uintptr(fd), nil, err
}
// InotifyRmWatch implements the inotify_rm_watch() syscall.
func InotifyRmWatch(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
fd := args[0].Int()
wd := args[1].Int()
ino, f, err := fdToInotify(t, fd)
if err != nil {
return 0, nil, err
}
defer f.DecRef()
return 0, nil, ino.RmWatch(wd)
}
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